An interfolding machine with separation fingers adjacent to respective interfolding rollers

ABSTRACT

The interfolding machine includes a first interfolding roller rotating around a first rotation axis and a second interfolding roller rotating around a second rotation axis parallel to the first rotation axis; wherein the first interfolding roller and the second interfolding roller form an interfolding nip therebetween. The interfolding machine further includes a first set of separation fingers associated with the first interfolding roller and arranged for reciprocatingly pivoting around a first pivoting axis parallel to the first rotation axis. The reciprocating pivoting movement of the first set of separation fingers is controlled by a first actuation mechanism including a first desmodromic cam. The interfolding machine also includes a second set of separation fingers associated with the second interfolding roller and arranged for reciprocatingly pivoting around a second pivoting axis parallel to the second rotation axis. The reciprocating pivoting movement of the second set of separation fingers is controlled by a second actuation mechanism including a second desmodromic.

TECHNICAL FIELD

The invention concerns interfolding machines. More specifically, the invention concerns improvements in reciprocatingly moving separation fingers combined to the interfolding rollers in order to detach folded sheets therefrom.

Background Art

Interfolding machines are commonly used in industry for manufacturing stacks of interfolded sheets. Interfolding machines are for example used for manufacturing stacks of interfolded tissue paper napkins or similar tissue paper articles.

Typically, an interfolding machine comprises counter-rotating interfolding rollers arranged one adjacent to the other and with parallel rotation axes, defining an interfolding nip between them. Sheets produced by cutting a continuous web material are fed alternatively to one and the other of said interfolding rollers. Each sheet is folded along a central folding line, thus forming two sheet portions. The two sheet portions of each sheet are placed between two sheet portions of a previous sheet and two sheet portions of a subsequent sheet, such as to form a stack of interfolded sheets.

To detach each folded sheet from the respective interfolding roller, two sets of reciprocatingly moving separation fingers are associated to the two interfolding rollers. The separation fingers are provided with a reciprocating pivotal movement around respective pivoting axes at a very high rate, corresponding to the production rate of the interfolding machine.

In order for higher production rates to be achieved, it would be beneficial to design separation fingers which are capable of moving at higher rates.

SUMMARY

According to an aspect, the present invention concerns an interfolding machine including a first interfolding roller rotating around a first rotation axis and a second interfolding roller rotating around a second rotation axis parallel to the first rotation axis. The first interfolding roller and the second interfolding roller together form an interfolding nip therebetween. According to embodiments disclosed herein, the interfolding machine further includes a first set of separation fingers, associated with the first interfolding roller and arranged for reciprocatingly pivoting around a first pivoting axis parallel to the first rotation axis, and a second set of separation fingers, associated with the second interfolding roller and arranged for reciprocatingly pivoting around a second pivoting axis parallel to the second rotation axis. The reciprocating pivoting movement of the first set of separation fingers and of the second set of separation fingers is controlled by a first actuation mechanism and by a second actuation mechanism, respectively. Each actuation mechanism comprises a respective desmodromic cam.

Additional features and embodiments of the interfolding machine of the present invention are set forth in the dependent claims and described in greater detail here on, reference being made to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 illustrates a schematic front view of an interfolding machine according to the invention;

FIG. 2 illustrates an enlargement of a portion of FIG. 1;

FIG. 3 illustrates a side view according to line III-III in FIG. 2;

FIGS. 4A-4C illustrate a sequence of operation in a first embodiment;

FIGS. 5A-5C illustrate a sequence of operation in a second embodiment;

FIG. 6 illustrates a view according to line VI-VI of FIG. 2;

FIG. 7 illustrates a sectional view according to line VII-VII of FIG. 6;

FIGS. 8A, 8B illustrate views according to line VIII-VIII of FIG. 7;

FIG. 9 illustrates a stack of interfolded sheets.

DETAILED DESCRIPTION

FIG. 1 illustrates a front view of an interfolding machine according to the invention. The interfolding machine 1 comprises a first feed path for a first continuous web N1 of tissue paper and a second feed path for a second continuous web N2 of tissue paper. Along the first path a first rotating cutting roller 3 is arranged, which is provided with angularly spaced blades 3A. The blades 3A co-act with a first stationary anvil blade 4. Along the second path a second rotating cutting roller 5 is arranged, which is provided with angularly spaced blades 5A. The blades 5A co-act with a second stationary anvil blade 6. The first cutting roller 3 rotates around a first rotation axis 3B and the second cutting roller 5 rotates around a second rotation axis 5B.

The first cutting roller 3 is further provided with suction ports 3C along the cylindrical surface thereof. The second cutting roller 5 is in turn provided with suction ports 5C along the cylindrical surface thereof. The suction ports 3C, 5C are aimed at retaining on the surface of the respective cutting rollers 3, 5 the sheets produced by cutting the continuous first and second webs N1, N2, and at transferring said sheets from the cutting rollers 3, 5 to interfolding rollers 9, 11.

The interfolding rollers 9, 11 rotate around respective rotation axes 9A, 11A, parallel to one another and parallel to the rotation axes of the cutting rollers 3, 5. The two interfolding rollers 9, 11 form an interfolding nip 13. Each interfolding roller 9, 11 is provided with respective folding members 15, 17. The folding members 15, 17 can provide suction means, or mechanical gripping means or both. Interfolding rollers and folding members are known to those skilled in the art and are not described in detail.

Each continuous web N1, N2 is guided around the respective rotating cutting roller 3, 5 and is fed between the cutting roller 3, 5 and the stationary anvil blade 4, 6. Co-action of the rotating blades 3A with the stationary anvil blade 4 cuts the continuous web N1 into individual sheets, which are then transferred from the first cutting roller 3 to the first interfolding roller 9. Similarly, the continuous web N2 is guided around the second cutting roller 5 and cut into sheets by co-action of the rotating blades 5A and the stationary anvil blade 6. The single sheets are then transferred from the second cutting roller 5 to the second interfolding roller 11.

A first set of separation fingers 21 are associated with the first interfolding roller 9. The first set of separation fingers 21 are best shown in FIGS. 6 and 7. The first interfolding roller 9 is provided with a plurality of annular grooves 9G. In the example shown in FIG. 6 there are seven annular grooves 9G and seven separation fingers 21 forming the first set of separation fingers. Each separation finger 9G coacts with a respective one of the annular grooves 9G, the first interfolding roller 9 is provided with.

A second set of separation fingers 23 are associated with the second interfolding roller 1. The second set of separation fingers 21 are best shown in FIGS. 6 and 7. The second interfolding roller 11 is provided with a plurality of annular grooves 11G. In the example shown in FIG. 6 there are seven annular grooves 11G and seven separation fingers 23 forming the first set of separation fingers. Each separation finger 11G co-acts with a respective one of the annular grooves 11G, the second interfolding roller 11 is provided with.

A different number of separation fingers and grooves can be provided.

The annular grooves 9G and 11G provide annular spaces which project inside the cylindrical surfaces of the first interfolding roller 9 and second interfolding roller 11. As shown in FIG. 7, each separation finger 21 can project in the respective annular groove 9G inside the cylindrical surface of the interfolding roller 9. Similarly, each separation finger 23 can project in the respective annular groove 11G inside the cylindrical surface of the interfolding roller 11.

The first set of separation fingers 21 are controlled by a respective first actuation mechanism 25, which will be described in greater detail later on. The first actuation mechanism 25 drives the first set of separation fingers 21 in a reciprocating pivoting movement around a first pivoting axis 21A, parallel to the rotation axis 9A of the first interfolding roller 9. As shown in FIG. 7, the pivoting axis 21A can be located on the cylindrical surface of the first interfolding roller 9, or inside said cylindrical surface. In FIG. 7 the two end positions of the reciprocating pivoting first set of separation fingers 21 are shown. In the first position, shown in dashed lines, the distal ends (i.e. the free ends opposite the pivoting axis 23A) of the first separation fingers 21 are arranged at least partly inside the annular grooves 9G. In the second position, shown in solid lines, the distal ends of the first separation fingers 21 are positioned outside the cylindrical surface of the first interfolding roller 9.

A symmetric arrangement is provided for the second set of separation fingers 23. The second set of separation fingers 23 are controlled by a respective second actuation mechanism 27, similar or identical to the first actuation mechanism 25. The second actuation mechanism 27 drives the second set of separation fingers 23 in a reciprocating pivoting movement around a second pivoting axis 23A, parallel to the rotation axis 11A of the second interfolding roller 11. As shown in FIG. 7, the pivoting axis 23A can be located on the cylindrical surface of the second interfolding roller 11, or inside said cylindrical surface. In FIG. 7 the two end positions of the reciprocating pivoting second set of separation fingers 23 are shown. In the first position, shown in solid lines, the distal ends of the second separation fingers 23 are arranged at least partly inside the annular grooves 11G. In the second position, shown in dashed lines, the distal ends of the second separation fingers 23 are positioned outside the cylindrical surface of the second interfolding roller 11.

As shown in FIG. 7, the pivoting movement of the first set of separation fingers 21 is in phase opposition with respect to the movement of the second set of separation fingers 23, such that when the first set of separation fingers 21 are inside the annular grooves 9G, the second set of separation fingers 23 are outside the annular grooves 11G and vice-versa. The separation fingers 21, 23 separate the folded sheets from the respective interfolding roller 9, 11 and place the sheets on a first or second pair of count combs, described below, to form a stack of interfolded sheets thereon.

In preferred embodiments, the first and second set of separation fingers 21, 23 move in synchronism with the folding members 15, 17 so that when a folding member is releasing a folded sheet S1 or S2 the separation fingers 21 or 23 detach or helps detaching the folded sheet form the respective interfolding roller 9, 11. The optimal motion law of the sets of separation fingers 21, 23 can be obtained using a respective desmodromic cam (to be described later on). The desmodromic cam can be assembled with the right phase respect to the folding rollers 9, 11.

The operation of the interfolding machine 1 in general is known from the art and does not require a detailed description. The co-action of the two interfolding rollers 9, 11 and of the sets of separation fingers 21, 23 produces stacks of interfolded sheets, one of which is schematically shown in FIG. 9 and labeled SK. Sheets S1 are delivered by the first interfolding roller 9 and sheets S2 are delivered by the second interfolding roller 11. Each sheet S1 has a central folding line F1, which divides the sheet S1 in two halves. Each sheet S2 has a central folding line F2, which divides the sheet S2 in two halves. The sheets S1, S2 are interfolded or interleaved, in the sense that each half portion of a sheet S1 is arranged between two half portions of a sheet S2 and vice-versa. Between two half portions of each sheet S2 half portions of two consecutive sheets S1 are placed. Similarly, between two half portions of each sheet S1 half portions of two consecutive sheets S2 are positioned. In this configuration, a folded sheet contains the trailing end of the previous sheet and the leading end of the next sheet, thus forming a stack SK of interfolded sheets.

Each first separation finger 21 is pivotally hinged to a respective stationary arm 29. The stationary arms 29 are integrally supported by a stationary frame 31, which can also support the first interfolding roller 9 and second interfolding roller 11. Similarly, each second separation finger 23 is pivotally hinged to a respective stationary arm 33. The stationary arms 33 are integrally supported by the stationary frame 31.

The stationary arms 29 and the stationary arms 33 extend from the stationary frame 31 in front of the respective interfolding rollers 9, 11 on the side opposite the arrival of the sheets in the interfolding nip 13. The stationary arms 29 and 33 project from the stationary frame 31 towards the interfolding nip 13. As best shown in FIG. 7, in this embodiment each stationary arm 29 extends towards the interfolding nip 13 beyond the rotation axis 9A of the first interfolding roller 9. Similarly, each stationary arm 33 extends from the stationary frame 31 towards interfolding nip 13 beyond the rotation axis 11A.

As shown in FIG. 7, each stationary arm 29 and each stationary arm 33 can have a proximal end constrained to the stationary frame 31 and a distal end extending towards the cylindrical surface of the respective interfolding roller 9 and 11. Preferably, as shown in FIG. 7, the distal end of each stationary arms 29 and 33 projects inside a respective one of the first annular grooves 9G and second annular grooves 11G.

The reciprocating pivoting movement of the first set of separation fingers 21 is transmitted from the first actuation mechanism 25 by means of respective connecting rods 35. The reciprocating pivoting movement of the second set of separation fingers 23 is transmitted from the second actuation mechanism 27 by means of respective connecting rods 37.

Reference number 35A designates the hinge point between the connecting rod 35 and the separation finger 21, while reference number 37A designates the hinge point between the connecting rod 37 and the separation finger 23.

The separation fingers 21, 23 and/or the connecting rods 35, 37 can be made of a light material, for instance aluminum, carbon fiber, plastic or resin, or fiber-reinforced resin, to reduce the mass and thus the inertia thereof.

The first actuation mechanism 25 comprises a first rotary shaft 39, which is provided with a reciprocating rotary motion around an axis 39A that extends parallel to the rotation axis 9A of the first interfolding roller 9 and distanced therefrom, i.e. the rotary shaft 39 is not coaxial with the respective interfolding roller 9. The second actuation mechanism 27 comprises similarly a symmetric second rotary shaft 41, which is provided with a reciprocating rotary motion around an axis 41A that is parallel to the rotation axis 11A of the second interfolding roller 11 and distanced therefrom, i.e. the rotary shaft 41 is not coaxial with the respective interfolding roller 11.

As best shown in FIG. 7, each connecting rod 35 is drivingly coupled to the first rotary shaft 39 by means of a respective crank 43; reference number 43A designates the hinge point between the crank 43 and the connecting rod 35. In a symmetrical way, each connecting rod 37 is drivingly coupled to the second rotary shaft 41 by means of a respective crank 45; reference number 45A designates the hinge point between the crank 45 and the connecting rod 35. The reciprocating rotary motion of the first rotary shaft 39 and the reciprocating rotary motion of the second rotary shaft 41 are transmitted through the cranks 43 and 45 and through the connecting rods 35 and 37 to the respective first set of separation fingers 21 and second set of separation fingers 23.

Referring again to FIG. 7, the distance between the rotation axis 39A (or the rotation axis 41A) and the hinge point 43A (or 45A) is labeled L1. The distance between the pivoting axis 21A (or 23A) and the hinge point 35A (or 37A) is labeled L2. In preferred embodiments L1 is greater than L2, such that a smaller angular movement of the rotary shafts 39 and 41 is sufficient to provoke a suitable oscillation of the separation fingers 21, 23.

Both ends of each connecting rod can be hinged to the respective separation fingers and the respective cranks by lubricated bearings, to reduce wear and increase the life time of the bearings.

According to the embodiment disclosed herein, the reciprocating rotary motion of the first rotary shaft 39 and second rotary shaft 41 is imparted by respective desmodromic cams. The desmodromic cam of the first actuation mechanism 25 is shown in FIGS. 8A, 8B. The desmodromic cam of the second actuation 27 is symmetrical and is not illustrated in the drawings. The desmodromic cam controlling the rotary motion of the first rotary shaft 39 is labeled 51 in FIGS. 8A, 8B. In this embodiment, the desmodromic cam 51 is a twin-body cam having a first cam body 51A and a second cam body 51B. The two cam bodies 51A, 51B are rigidly constrained to one another and form together the desmodromic cam 51. The first cam body 51A has a first cam profile 53A and the second cam body 51B has a second cam profile 53B. The desmodromic cam 51 co-acts with a rocking arm 57 constrained to the first rotary shaft 39. The rocking arm 57 is a double arm, i.e. an L-shaped arm, having two distal ends. The two distal ends support each a respective roller, wheel or another contacting body which co-acts with one of the cam profiles 53A, 53B. The first contacting body and the second contacting body are shown at 59A and 59B. The first contacting body 59A contacts the first cam profile 53A and the second contact body 59B contacts the second cam profile 53B.

A continuous rotation motion according to arrow f51 of the desmodromic cam 51 is thus converted into a reciprocating rotary motion (arrow f39) of the rotary shaft 39 around axis 39A. The rotation of the rotary shaft 39 in both directions (clockwise and counterclockwise) is positively controlled by the two cam profiles 53A, 53B of the desmodromic cam 51. This enables very high reciprocating rotation motions to be achieved and thus to achieve a high production rate of the interfolding machine 1.

A different desmodromic cam can be provided, for instance a cam with a channel, into which a single contacting member is located. The contacting member contacts opposite cam profiles formed by opposite side walls of the channel.

The second rotary shaft 41 can be controlled by a symmetrical mechanism, with a desmodromic cam, not shown, which can be designed in the same way as the desmodromic cam shown in FIG. 8A, 8B.

The desmodromic cams can be housed in respective boxes 61, 63 (FIG. 6). The rotary motion of the desmodromic cams 51 can be obtained by the continuous rotary motion of the respective first and second interfolding roller 9, 11 as follows. A first toothed wheel 71 can be keyed on a first shaft 73 of the first interfolding roller 9. A second toothed wheel 75 can be keyed on a second shaft 77 of the second interfolding roller 11. The first toothed wheel 71 and the second toothed wheel 75 mesh with one another such that the first interfolding roller 9 and the second interfolding roller 11 can rotate in opposite directions (arrows f9, f11 in FIG. 6) under the control of a motor, schematically shown at 81 in FIG. 6. A respective first pinion 83 meshes with the first toothed wheel 71. The first pinion 83 can be keyed on a first cam shaft 85, on which the desmodromic cam 51 can be keyed (FIGS. 8A, 8B). Similarly, a second pinion 87 meshes with the second toothed wheel 75 and is keyed on a second cam shaft 89, on which there is keyed the desmodromic cam (symmetrical to cam 51 and not shown) controlling the reciprocating pivoting movement of the second rotary shaft 41. As show in the figures, see e.g. FIG. 6, and FIGS. 8A, 8B, the first and second cam shafts 85, 89 are parallel to the rotation shafts 73 and 77 and relevant rotation axes 9A, 11A of the interfolding rollers 9, 11, but distanced therefrom, i.e. not coaxial thereto, such that the desmodromic cams rotate around axes which are separate and distanced from (non-coaxial to) the rotation axes 9A, 11A of the interfolding rollers 9, 11.

Thus, a first gear train connection 71, 83 transmits the rotation motion from the first interfolding roller 9 to the first desmodromic cam 51 and a second gear train connection 75, 87 transmits the rotation motion from the second interfolding roller 11 to the second desmodromic cam (not shown and symmetrical to cam 51). In this way, the rotary motions of the desmodromic cams and the reciprocating motions of the rotary shafts 39, 41 (and thus of the separation fingers 21, 23) are synchronized with the rotary motion of the interfolding rollers 9, 11.

In other embodiments, a different transmission arrangement can be provided, for instance using endless belts to transmit the motion from the interfolding rollers 9, 11 to the desmodromic cams. Using a gear train, however, may be beneficial in terms of better control of the movement.

The use of desmodromic cams to control the oscillating movement of the separation fingers 21, 23 can be beneficial in at least two respects. Firstly, these cams allow a very high frequency of the reciprocating pivoting movement to be achieved with a good motion control. A number of oscillations per minute of the separation fingers as high as 25 oscillations per second or higher can be achieved. Secondly, it is possible to easily change the law of motion of the separation fingers by replacing the desmodromic cams with another set of desmodromic cams having different cam profiles.

While according to the embodiment illustrated in the drawings the desmodromic cams 51 are driven into rotation by the same motor 81 that drives into rotation the interfolding rollers 9, 11, in other embodiments an independent electric motor can be provided for each desmodromic cam. In yet further embodiments, a single electric motor, independent from motor 81, can be provided to drive into rotation both desmodromic cams. If one or two independent motors are used to drive the desmodromic cams, such motors will be electronically controlled such as to rotate in synchronism with the interfolding rollers 9, 11. If independent motors are used for the desmodromic cams on the one side and the interfolding rollers on the other, the phase between the interfolding rollers and the desmodromic cams can be tuned easily, e.g. by acting upon one of said motors, typically upon the motor(s), which controls the rotation of the desmodromic cams.

According to some embodiments, the desmodromic cam profiles can be adapted to impart different motion speeds to the separation fingers 21, 23 during the removing motion and the returning motion, i.e. during the pivoting movement away from the interfolding rollers 9, 11 and during the pivoting movement towards the interfolding rollers 9, 11. More specifically, according to some embodiments, the moving-away movement, i.e. the movement by which the separation fingers 21, 23 detach the folded sheet from the respective interfolding roller 9, 11 can be slower than the return movement. In other embodiments, the opposite can be provided, i.e. the moving-away movement can be faster than the return movement. The choice of which movement is faster can depend upon, inter alia, the features of the material (tissue paper, for instance) of which the sheets are made, upon the number of sheets per stack, the number of plies per sheet, and so on. A slower moving away motion can be beneficial, for instance, in order to have a gentler action on the tissue paper preventing damages thereto when the sheets are detached from the interfolding rollers 9, 11.

In order to form stacks of interfolded sheets S1, S2 containing a predetermined number of sheets, pairs of count combs can be provided, as will be described here below, referring specifically to FIGS. 1 to 5.

More specifically, referring in particular to FIG. 2, a first pair of count combs 91, 93 are symmetrically arranged in front of the interfolding nip 13, on the side where the separation fingers 21, 23 are located. A second pair of count combs 95, 97 is further symmetrically arranged in front of the interfolding nip 13.

For the sake of clarity, FIG. 2 illustrates the two pairs of count combs 91, 93, 95, 97, while the separation fingers 21, 23 are omitted. In FIG. 7, described in greater detail above, the count combs 91, 93, 95, 97 are omitted, to show in more detail the structure of the separation fingers 21, 23. FIG. 1 illustrates both the separation fingers and the count combs in combination, to better show their mutual position.

Each count comb is movable according to a first direction and a second direction along two translation axes X and Y. Axis X is orthogonal to the rotation axes 9A, 11A of the interfolding rollers 9, 11, and parallel to a plane containing the rotation axes 9A, 11A. Axis Y is orthogonal to axis X and to the rotation axes 9A, 11A. The movement according to axes X and Y is independently controlled for each count comb 91, 93, 95 and 97, in that each count comb has its own driving unit. However, these movements are synchronized with one another and coordinated with each other, in a manner to be described below, in order to form sequences of stacks of folded sheets. The driving units of combs 91, 93, 95, 97 are labeled 101, 103, 105 and 107 respectively. The driving units can be interfaced to a single control unit, such that their movements can be synchronized.

The driving units 101 and 105 are substantially identical to one another and are in turn substantially symmetrical to the driving units 103, 107. The following detailed description therefore applies to all four driving units 101-107. The structure of a driving unit 103-107 is now described in more detail with reference to FIGS. 2 and 3.

Each driving unit comprises a first electronically controlled electric motor 121 supported by a carriage 123. The carriage 123 supports a rotating shaft 125, which extends parallel to the rotation axes 9A, 11A of the first interfolding roller 9 and of the second interfolding roller 11. Two toothed wheels 127A, 127B are keyed at the ends of shaft 125. The toothed wheel 127B meshes with an output gear 129 of the first electric motor 121, such that the rotation of electric motor 121 is transmitted to both toothed wheels 127A, 127B.

The toothed wheels 127A, 127B mesh with respective toothed racks 131A, 131B, which form part of a slide 133. The slide 133 includes side panels 135, on which the toothed racks 131A, 131B are mounted. The side panels 135 are connected to one another by a beam that forms part of the respective count comb and supports teeth or prongs of the respective count comb. In FIG. 3 the beam is labeled 93B and the prongs or teeth are numbered 93A, and they cumulatively form the count comb 93. As noted above the remaining count combs 91, 95 and 97 are substantially the same or symmetrical to count comb 93 and therefore they also have a beam supporting respective prongs, the beam and the prongs forming part of the respective slide 133.

The slide 133 is reciprocatingly movable along the translation axis X with respect to the respective carriage 123. The reciprocating movement along the translation X is controlled by the first electric motor 121. For the slide 133 to be guided with respect to the corresponding carriage 123 guides 137 are provided, extending along the translation axis X.

The carriage 123 of each driving unit 101, 103, 105, 107 is constrained to a flexible endless member 141. In the embodiment shown in the drawings the flexible endless member 141 comprises two toothed belts which are guided around respective upper and lower pulleys 143, 145. The upper pulleys 143 can be idly mounted on the stationary frame 31. The lower pulleys 145 can be keyed on a shaft 147, which can be driven into reciprocating rotation by a second electronically controlled electric motor 149. The rotation of the second electric motor 149 drives the carriage 123 along the axis Y. The second electric motor 149 rotates selectively clockwise and counter-clockwise to move the carriage 123 up and down along axis Y.

The above described arrangement is common to all driving units 101, 103, 105, 107. Thus, each driving unit can control the reciprocating movement of the respective count comb 91, 93, 95, 97 in the two directions parallel to axis X and axis Y. A control unit 151 (FIG. 3) can be interfaced with each first and second electric motor 121, 149 of each count comb 91, 93, 95, 97, for electronically controlling the electric motors and thus the movement of the count combs, in order to form stacks SK of folded sheets S1, S2.

By providing driving units having the same structure for each one of the four count combs 91, 93, 95, 97, construction and maintenance of the interfolding machine are made simpler. The same spare parts can be used for all driving units. Also, it is possible to have just one spare driving unit in order to replace any one of the four driving units present in the interfolding machine, in case of default.

The operation of the count combs 91, 93, 95, 97 can be controlled in different ways. Two different possible sequences of operation of the count combs are show in FIGS. 4A, 4B, 4C and 5A, 5B, 5C, respectively, and will be shortly described here below. The movement of the count combs is controlled such that stacks of a predetermined number of interfolded sheets can be produced.

Referring to FIGS. 4A, 4B, 4C the two pairs of count combs 91, 93, 95, 97 are controlled to perform the same operations, i.e. the first pair of count combs 91, 93 performs the same operation as the second pair of count combs 95, 97, but in an alternated manner, i.e. in a timely shifted manner. In FIG. 4A, the second pair of count combs 95, 97 is moving downwards (direction Y) to remove a first stack SK1 of folded sheets S1, S2 from the interfolding rollers 9, 11, such that a second stack SK2 of folded sheets S1, S2 can be formed on the first pair of count combs 91, 93, which are positioned just under the interfolding rollers 9, 11, in front of the interfolding nip 13.

In FIG. 4B the first pair of count combs 91, 93 has moved downwards for a short stroke, to allow the second stack SK2 to grow, while the first stack SK1 has been discharged by the second pair of count combs 95, 97. In this step the first pair of count combs 91, 93 which are supporting the stack SK2 under formation moves downwards approximately at the speed of stack growing, i.e. at the speed at which the height of the stack under formation gradually increases.

The second pair of count combs 95, 97 can release the stack SK1 on a conveyor which removes the stack SK1 in a direction orthogonal to the figure.

After unloading the first stack SK1, the second pair of count combs 95, 97 has been brought in an upper position (moving along the respective axes Y). In FIG. 4B the second pair of count combs 95, 97 is in an idle position. The combs 95, 97 are spaced apart from one another along the direction of axis X, such that at this stage they do not interfere with the operation of the interfolding rollers 9, 11 and of the separation fingers 21, 23 (not shown in the sequence of FIGS. 4A, 4B, 4C), which continue forming the second stack SK2 on the first pair of count combs 91, 93, which move gradually downwards.

Once the required number of interfolded sheets S1, S2 have been stacked on the first pair of count combs 91, 93, the second pair of count combs 95, 97 move towards one another in the direction of the axis X, thus separating the stack SK2 from the next incoming sheets. At the same time or immediately thereafter the count combs 91, 93 move downwards (along axis Y). In this way a third stack SK3 can start forming on the second pair of count combs 95, 97, as shown in FIG. 4C, while the first pair of count combs 91, 93 are moving downwards (along the direction of the axis Y), to remove the second stack SK2.

As can be understood from the short description above and referring to FIGS. 4A, 4B, 4C, the two pairs of count combs 91, 93 and 95, 97 perform the same action on sequentially formed stacks of sheets. This can be beneficial in terms of machine programming, since the control software becomes simpler.

When the pair of count combs 91, 93 or the pair of count comb 95, 97 is in the lower position, the stack supported thereon can be unloaded on an evacuation conveyor, such as an evacuation belt, for instance, which can extend orthogonal to the FIGS. 4A-4C, i.e. parallel to the axes 9A, 11A. In the mode of operation of FIGS. 4A, 4B, 4C, both pairs of count fingers 91, 93 and 95, 97 are adapted to perform a stroke from an upper position adjacent the interfolding nip 13 (see e.g. count combs 95, 97 in FIG. 4B, to a lower, evacuation position, adjacent the evacuation belt, see e.g. count combs 95, 98 in FIG. 4A.

The one disclosed with reference to FIGS. 4A, 4B, 4C is not the only possible way of operating the count combs, however. In the sequence of FIGS. 5A, 5B, 5C each stack SK1, SK2, SK3 is formed partly on the same pair of count combs 91, 93 and partly on the count combs 95, 97. Only the count combs 95, 97 are in charge of discharging the formed stacks on the removing conveyor. In other words, each stacking cycle is performed partly on the first pair of count combs 91, 93 and partly on the second pair of count combs 95, 97.

During the initial step of stack formation, each stack SK1, SK2, SK3 is supported by the count combs 91, 93 until a step, at which the stack is transferred from the first pair of count combs 91, 93 to the second pair of count combs 95, 97.

More specifically, when the first pair of count combs 91, 93 and the second pair of count combs 95, 97 are at the same level, i.e. at the same height, the count combs 91, 93 are opened, i.e. are distanced from one another in the direction of axis X, to discharge the stack under formation on the second pair of count combs 95, 97, which are waiting in a dwelling position. Once the stack under formation has been transferred on the second pair of count combs 95, 97, the first pair of count combs 91, 93 are moved upwards and returned to a position adjacent the interfolding, where they will wait for the next stacking cycle to begin.

Meanwhile the second pair of count combs 95, 97 are moved downwards at the stack forming speed supporting the growing stack. When the first stack SK1 is completed the count combs 91, 93 are closed again (i.e. are moved close to one another along axes X), while the second pair of count combs 95, 97 are moved further downwards (axis Y) at a speed greater than the stack growing speed. Once the second pair of count combs 95, 97 have reached a discharging position, they are spaced apart from one another (movement along axis X) to discharge the stack just received from the first pair of count combs 91, 93.

As soon as the stack SK1 has been discharged from the second pair of count combs 95, 97, these latter are moved upwards (direction of axis Y) and moved again close to one another (direction of axis X) in a position under the first pair of count combs 91, 93. The second pair of count combs 95, 97 are thus correctly positioned to receive the next stack SK2 being formed and temporarily supported by the first pair of count combs 91, 93.

The position where the stack being formed is transferred from the first pair of count combs 91, 93 to the second pair of count combs 95, 97 can be adjusted according to needs and can be selected based upon the number of sheets per stack and can be selected such that the dynamic of the count combs 91, 93 and 95, 97 is optimized, i.e. the dynamic load thereon is minimized.

The stack separation is obtained inserting at high speed the count combs 91, 93 in the sheets flow. Each count comb is inserted (movement along axis X) in phase with the sheet and the separation fingers 21, 23. When the second to last sheet is detached from the relative interfolding roller and it is set down on the stack by the relative separation finger (the distal end of the separation fingers is positioned outside the cylindrical surface of the first interfolding roller 9) the first count comb is inserted. When the last sheet is stacked and the relative separation finger is still on the stack, the second count comb is inserted completing the stack separation. The second count comb is one sheet out of phase respect to the first count comb. During the separation phase or immediately after the separation phase, the count combs 91, 93 are moved downwardly supporting the advancing of the new stack. According to the operation mode shown FIGS. 5A, 5B, 5C, therefore, the first pair of count combs 91, 93 moves up and down (axis Y) for a short stroke, required to allow the stack under formation to grow between the interfolding rollers 9, 11 and the first pair of count combs 91, 93. Conversely, the second pair of count combs 95, 97 performs a longer vertical stroke, to remove each stack away from the pair of interfolding rollers 9, 11.

In both operation modes (FIGS. 4A-4C and FIGS. 5A-5C) the movement in the direction of the axis X of the count combs can be tuned to facilitate the separation of a completed stack SK from the flow of incoming interfolded sheets delivered by the interfolding rollers 9, 11. To this end, for instance, the approaching movement along the direction of the axis X of the count combs which separate the completed stack from the next sheet can be out of phase, in that the movement of one of the two count combs is started before the other. In other words the approaching movement of the count combs in the X direction can be non-symmetric, i.e. non-synchronous.

The movement of the count combs is moreover synchronized with the pivoting movement of the separation fingers 21, 23 to facilitate the separation each completed stack SK from the incoming continuous flow of interfolded sheets from the interfolding nip 13.

The following clauses set forth combinations of inventive features, which specifically form part of the present disclosure:

Clause 1. An interfolding machine comprising:

a first interfolding roller rotating around a first rotation axis;

a second interfolding roller rotating around a second rotation axis parallel to the first rotation axis; wherein the first interfolding roller and the second interfolding roller form an interfolding nip therebetween;

folding members arranged on the first interfolding roller and second interfolding roller;

a first set of separation fingers associated with the first interfolding roller and arranged for reciprocatingly pivoting around a first pivoting axis parallel to the first rotation axis and adjacent to the first interfolding roller;

a second set of separation fingers associated with the second interfolding roller and arranged for reciprocatingly pivoting around a second pivoting axis parallel to the second rotation axis and adjacent to the second interfolding roller.

Clause 2. The interfolding machine of clause 1, wherein the first pivoting axis is arranged on or inside the cylindrical surface of the first interfolding roller and the second pivoting axis is arranged on or inside the cylindrical surface of the second interfolding roller.

Clause 3. The interfolding machine of clause 1, wherein each separation finger of the first set of separation fingers is pivotally supported by a respective stationary arm constrained to a stationary frame and is drivingly coupled to a first actuation mechanism by a respective first connecting rod; and wherein each separation finger of the second set of separation fingers is pivotally supported by a respective stationary arm constrained to the stationary frame and is drivingly coupled to a second actuation mechanism by a respective second connecting rod.

Clause 4. The interfolding machine of clause 2, wherein each separation finger of the first set of separation fingers is pivotally supported by a respective stationary arm constrained to a stationary frame and is drivingly coupled to a first actuation mechanism by a respective first connecting rod having a first end hinged to the separation finger; and wherein each separation finger of the second set of separation fingers is pivotally supported by a respective stationary arm constrained to the stationary frame and is drivingly coupled to a second actuation mechanism by a respective second connecting rod having a first end hinged to the separation finger.

Clause 5. The interfolding machine of clause 3, wherein each stationary arm of the first set of separation fingers extends from the stationary frame in front of the first interfolding roller beyond the first rotation axis towards the interfolding nip; and wherein each stationary arm of the second set of separation fingers extends from the stationary frame in front of the second interfolding roller beyond the second rotation axis towards the interfolding nip.

Clause 6. The interfolding machine of clause 4, wherein each stationary arm of the first set of separation fingers extends from the stationary frame in front of the first interfolding roller beyond the first rotation axis towards the interfolding nip; and wherein each stationary arm of the second set of separation fingers extends from the stationary frame in front of the second interfolding roller beyond the second rotation axis towards the interfolding nip.

Clause 7. The interfolding machine of clause 5, wherein each stationary arm of the first set of separation fingers has a proximal end constrained to the stationary frame and a distal end projecting in a respective annular groove of the first interfolding roller; and wherein each stationary arm of the second set of separation fingers has a proximal end constrained to the stationary frame and a distal end projecting in a respective annular groove of the second interfolding roller.

Clause 8. The interfolding machine of clause 6, wherein each stationary arm of the first set of separation fingers has a proximal end constrained to the stationary frame and a distal end projecting in a respective annular groove of the first interfolding roller; and wherein each stationary arm of the second set of separation fingers has a proximal end constrained to the stationary frame and a distal end projecting in a respective annular groove of the second interfolding roller.

Clause 9. The interfolding machine of any one of clauses 3 to 8, wherein the first actuation mechanism comprises a first rotary shaft provided with a reciprocating rotary motion around an axis parallel to the first rotation axis of the first interfolding roller; wherein each first connecting rod is coupled to the first rotary shaft by a respective first crank, whereto a second end of the first connecting rod is hinged, such that the reciprocating rotary motion of the first rotary shaft is transmitted through the first cranks and the first connecting rods to the separation fingers of the first set of separation fingers; wherein the second actuation mechanism comprises a second rotary shaft provided with a reciprocating rotary motion around an axis parallel to the second rotation axis of the second interfolding roller; wherein each second connecting rod is coupled to the second rotary shaft by a respective second crank, whereto a second end of the second connecting rod is hinged, such that the reciprocating rotary motion of the second rotary shaft is transmitted through the second cranks and the second connecting rods to the separation fingers of the second set of separation fingers.

Clause 10. The interfolding machine of clause 9, wherein the first actuation mechanism comprises a desmodromic cam control mechanism; and wherein the second actuation mechanism comprises a desmodromic cam control mechanism.

Clause 11. The interfolding machine of clause 10, wherein the first desmodromic cam control mechanism comprises a first desmodromic cam driven into rotation by a first gear train connection between a first cam shaft and the first folding roller; and wherein the second desmodromic cam control mechanism comprises a second desmodromic cam driven into rotation by a second gear train connection between a second cam shaft and the second folding roller.

Clause 12. The interfolding machine of clause 11, wherein the first desmodromic cam comprises a double cam profile co-acting with a first rocking arm, mounted on the first rotary shaft for co-rotation therewith; and wherein the second desmodromic cam comprises a double cam profile co-acting with a second rocking arm, mounted on the second rotary shaft for co-rotation therewith. 

1-17. (canceled)
 18. An interfolding machine comprising: a first interfolding roller rotating around a first rotation axis; a second interfolding roller rotating around a second rotation axis parallel to the first rotation axis; wherein the first interfolding roller and the second interfolding roller form an interfolding nip therebetween; a cutting arrangement adapted to divide continuous web material into separate sheets; wherein the first interfolding roller and the second interfolding roller are adapted to interfold sheets delivered from the cutting arrangement; a first set of separation fingers associated with the first interfolding roller and arranged for reciprocatingly pivoting movement around a first pivoting axis parallel to the first rotation axis; wherein the reciprocatingly pivoting movement of the first set of separation fingers is controlled by a first actuation mechanism comprising a first desmodromic cam; a second set of separation fingers associated with the second interfolding roller and arranged for reciprocatingly pivoting movement around a second pivoting axis parallel to the second rotation axis; wherein the reciprocatingly pivoting movement of the second set of separation fingers is controlled by a second actuation mechanism comprising a second desmodromic cam.
 19. The interfolding machine of claim 18, further comprising a first feed path for a first continuous web and a second feed path for a second continuous web; wherein the cutting arrangement comprises cutters adapted to divide the first continuous web and a second continuous web into sheets, said sheets being delivered to the first interfolding roller and the second interfolding roller.
 20. The interfolding machine of claim 18, wherein the first desmodromic cam is driven into rotation by a first gear train connection between the first interfolding roller and a first cam shaft, on which the first desmodromic cam is mounted for co-rotation therewith; and wherein the second desmodromic cam is driven into rotation by a second gear train connection between the second interfolding roller and a second cam shaft, on which the second desmodromic cam is mounted for co-rotation therewith.
 21. The interfolding machine of claim 18, wherein the first interfolding roller and the second interfolding roller are driven into rotation by a first motor, and wherein the first desmodromic cam of the first actuation mechanism and the second desmodromic cam of the second actuation mechanism are driven into rotation by a single additional motor, or by two separate additional motors, different from the first motor which drives into rotation the first interfolding roller and the second interfolding roller.
 22. The interfolding machine of claim 18, wherein each of the first desmodromic cam and the second desmodromic cam comprise a first cam profile and a second cam profile co-acting with a respective rocking arm, configured for transmitting the reciprocating pivoting movement to the respective set of separation fingers.
 23. The interfolding machine of claim 22, wherein the first cam profile and the second cam profile of each of the first desmodromic cam and the second desmodromic cam co-act with a first contacting body and a second contacting body, respectively.
 24. The interfolding machine of claim 22, wherein the first cam profile and the second cam profile are configured to control oscillation motion of respectively the first set of separation fingers and the second set of separation fingers at a higher speed when moving away from respectively the first interfolding roller and the second interfolding roller, and at slower speed when moving towards respectively the first interfolding roller and the second interfolding roller.
 25. The interfolding machine of claim 18, wherein each separation finger of the first set of separation fingers is pivotally supported by a stationary frame and is drivingly coupled to the first actuation mechanism by a respective first connecting rod, a first end whereof is hinged to respectively said each separation finger of the first set of separation fingers; and wherein each separation finger of the second set of separation fingers is pivotally supported by the stationary frame and is drivingly coupled to the second actuation mechanism by a respective second connecting rod, a first end whereof is hinged to respectively said each separation finger of said second set of separation fingers.
 26. The interfolding machine of claim 25, wherein a second end of the first connecting rod is hinged to a first rotary shaft of the first actuation mechanism provided with a reciprocating rotary motion around an axis parallel to the rotation axis of the first interfolding roller; and a second end of the second connecting rod is hinged to a second rotary shaft of the second actuation mechanism, provided with a reciprocating rotary motion around an axis parallel to the rotation axis of the second interfolding roller; wherein the first rotary shaft and the second rotary shaft are driven into reciprocating rotation by respectively the first desmodromic cam and the second desmodromic cam.
 27. The interfolding machine of claim 25, wherein the first actuation mechanism comprises a first rotary shaft provided with a reciprocating rotary motion around an axis parallel to the first rotation axis of the first interfolding roller; wherein each first connecting rod is coupled to the first rotary shaft by a respective first crank, whereto the second end of the first connecting rod is hinged, such that the reciprocating rotary motion of the first rotary shaft is transmitted through respective ones of the first cranks and the first connecting rods to the separation fingers of the first set of separation fingers; wherein the second actuation mechanism comprises a second rotary shaft provided with a reciprocating rotary motion around an axis parallel to the second rotation axis of the second interfolding roller; wherein each said second connecting rod is coupled to the second rotary shaft by a respective second crank, whereto the second end of the second connecting rod is hinged, such that the reciprocating rotary motion of the second rotary shaft is transmitted through respective ones of the second cranks and the second connecting rods to the separation fingers of the second set of separation fingers; wherein the first rotary shaft is driven into reciprocating pivoting movement by the first desmodromic cam; and wherein the second rotary shaft is driven into reciprocating pivoting movement by the second desmodromic cam.
 28. The interfolding machine of claim 27, wherein a rocking arm of each of the first actuation mechanism and the second actuation mechanism is mounted on a respective one of the first rotary shaft and the second rotary shaft for co-rotation therewith, the rotation of respectively the first desmodromic cam and the second desmodromic cam being transformed into the reciprocating pivoting movement of the rotary shaft by said rocking arm.
 29. The interfolding machine of claim 27, wherein the distance between the axis of each of the first rotary shaft and the second rotary shaft and the pivoting point between respectively the first crank and the second crank is greater than distance between the pivoting axis of respective separation fingers of the first set of separation fingers and the second set of separation fingers and the hinge point between said separation finger and respectively the first connecting rod and the second connecting rod.
 30. The interfolding machine of claim 18, wherein the first pivoting axis is adjacent to the first interfolding roller; and the second pivoting axis is adjacent to the second interfolding roller.
 31. The interfolding machine of claim 29, wherein the first pivoting axis is arranged on or inside a cylindrical surface of the first interfolding roller and the second pivoting axis is arranged on or inside a cylindrical surface of the second interfolding roller.
 32. The interfolding machine of claim 18, wherein each separation finger of the first set of separation fingers is pivotally supported on a respective first stationary arm which extends in front of the first interfolding roller beyond the first rotation axis towards the interfolding nip; and wherein each separation finger of the second set of separation fingers is pivotally supported on a respective stationary arm which extends in front of the second interfolding roller beyond the second rotation axis towards the interfolding nip.
 33. The interfolding machine of claim 18, wherein the first desmodromic cam is mounted on a respective first cam shaft for rotation therewith, and the second desmodromic cam is mounted on a respective second cam shaft for rotation therewith, the first cam shaft and the second cam shaft being parallel to and distanced from the rotation axes of the first interfolding roller and second interfolding roller. 